Federal and state health and safety standards mandate that industrial food service companies and manufacturing facilities perform routine testing for common bacteria, such as Salmonella species, E. coli O157:H7, and Listeria monocytogenes, that cause food-borne illnesses. As a safety precaution, companies are required to perform testing on each batch or lot of food prior to the food reaching the public. Several methods are currently available for industrial testing of bacteria in the food service industry.
However, there are currently severe limitations on the tests available to the industry. Present methods utilized as industry standards require 2-5 days to perform. For example, the most widely used methods for detection of Salmonella employ a pre-enrichment (day 1), a selective enrichment (day 2), and a final enrichment followed by an immunoassay requiring 105 organisms (day 3); the most widely used methods of detection of E. coli O157:H7 employ a selective enrichment (8-28 hours) and an immunoassay requiring 105 organisms; the most widely used methods of detection of Listeria monocytogenes employ a pre-enrichment (26-30 hours), an enrichment (22-26 hours), and an immunoassay requiring 105 organisms. For the detection of E. coli O157:H7 and Listeria monocytogenes, all samples that are suspected as positive by the immunoassay must be confirmed by culture methods (1-3 days for E. coli O157:H7 and 4-5 days for Listeria monocytogenes). Thus, in many cases, the food suppliers must wait days for test results before shipping their already manufactured products. As a result, the company may lose profits from a reduced shelf life and the wait also increases the potential for food spoilage.
In addition, using methods now available in the art, the organism needs to be cultured to a concentration of at least 105/ml to be detected. Because the margin of error in detectability of the bacteria is high, false negative tests may result and a food poisoning outbreak may occur. The company is then forced to recall product that has already reached the consumer. This places the public at a great health risk. The manufacturer or producer is also forced to bear the costs of recall, and is at a risk for lawsuit or government mandated shutdown of production facilities.
Thus, there is a need for an inexpensive testing technology that provides a rapid turn-around time, and a high degree of accuracy and reproducibility, which will result in safer food manufacturing and preparation. Additionally, there is a need for a method that keeps pace with new manufacturing processes. Polymerase chain reaction (“PCR”) testing technology for food-borne pathogenic bacteria facilitates rapid and accurate testing for the manufacturers.